Field of the Invention
The invention relates to an orthotic fitting having a knee guide joint, with which it is possible, unilaterally with one fitting, or bilaterally with opposite fittings, to connect a lower leg mounting part and an upper leg mounting part of the orthosis to each other in an articulated manner as a knee joint support. For this purpose, such a fitting has two leg parts, which can be rigidly connected to the lower leg mounting part and to the upper leg mounting part, respectively, and of which the leg ends directed toward each other are component parts of the knee guide joint. The expressions lower leg mounting part and upper leg mounting part are understood in general as all devices, such as shell parts, strap elements, cuffs, bandages, etc, with which an orthotic fitting can be secured and fixed with its two leg parts in a predetermined position on the lower leg and upper leg of a patient.
In generally known knee orthoses of this kind, the knee guide joints of the orthotic fittings are in most cases designed as simple rotary joints. The range of pivoting is optionally determined and limited by abutments. For example, such knee orthoses are applied after cruciate ligament surgery, as a result of which the relative movement between lower leg and upper leg is possible only within the context of the kinematics of the knee orthosis in association with a stabilization of the knee.
The pivot geometry of the human knee corresponds not to a rotary joint but to a sliding pivot joint in which the pivot axis shifts spatially depending on the pivot angle. The pivoting movement forced on the knee by the knee orthosis via the rotary joints of the orthotic fittings does not therefore correspond to the pivoting movement of the knee, such that the knee, from which the load is intended to be taken up by the orthosis, is subjected unfavorably to constraining forces in certain ranges of pivoting. These constraining forces can be slightly reduced in a manner known per se if the rotary joints of the orthosis are positioned slightly above the knee joint, although unfavorable constraining forces still act on the knee joint in this arrangement too.
In order to provide an improvement in this respect, polycentric knee orthoses (DE 199 33 197 B4) with a joint mechanism are therefore already known which have two spaced-apart pivot axes for the pivotable bearing of the distal leg and the proximal leg of an orthotic fitting. In addition, the leg ends mesh with each other via teeth, and adjustable abutments are provided for limiting the range of pivoting. Knee orthoses of this kind with two axes are intended, with their pivot geometry, to simulate the natural sequence of movement during flexion of the knee joint and to do so better than the knee orthoses described above with only single-axis orthotic fittings. On the one hand, however, constraining forces still act on the knee joint in this case too, since once again the simulation of the natural movement is incomplete, and, on the other hand, the orthotic fitting with a toothed joint is complex and expensive.